#include <iostream>
#include <windows.h>
using namespace std;

int factorial(int num);

int main()
{
        int n;
        cout << "Enter a number and press ENTER: ";
        cin >> n;
        cout << "Function returned: " << factorial(n);
        system("pause");
        return 0;
}

int factorial(int n)
{
        int i;
        int um;
        for(i = 1; i <= n; i++)
        um *= i;
        return um;
}

um *= i;